Liquid crystal display device

ABSTRACT

The object of the present invention is to make parts and kinds of liquid crystal display devices in common for cope stably and flexibly with commercial products of computer makers and television makers which have been promoted in various kinds, for simplifying maintenance of a liquid crystal display unit mounted on computers, display monitors therefor or televisions, and preferably for enabling to omit positional adjustment of a light source unit and a liquid crystal display panel during the maintenance of the liquid crystal display device. For this object, the invention provides a liquid crystal display device comprising first, second, and third housings, a liquid crystal display panel fixed between the first and second housings, a light source (cold-cathode fluorescent tubes) fixed to the third housing, the second and third housings being detachable to one another, being constructed by overlapping the first, second and third housings with each other, wherein a timing-converter board fixed to an opposite side surface of the third housing to a side surface to which the light source is fixed, and protrusions formed on the opposite side surface so as to determine a maximum thickness of the liquid crystal display device.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a Continuation of U.S. application Ser. No.12/078,014 filed on Mar. 26, 2008 now U.S. Pat. No 7,834,950, which is aContinuation of U.S. application Ser. No. 11/252,848 filed on Oct. 19,2005 now U.S. Pat. No. 7,432,997, which is a Continuation of U.S.application Ser. No. 09/671,429 filed on Sep. 27, 2000 now U.S. Pat. No.6,992,734. Priority is claimed from U.S. application Ser. No. 12/078,014filed on Mar. 26, 2008, which claims priority from U.S. application Ser.No. 11/252,848 filed on Oct. 19, 2005, which claims priority from U.S.application Ser. No. 09/671,429 filed on Sep. 27, 2000, which claims thepriority of Japanese Patent Application 11-278844 filed on Sep. 30,1999, all of the contents of which are hereby incorporated by referenceinto this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a liquid crystal display device used for amonitor for laptop personal computers, desktop computers or the like,and a liquid crystal display monitor using the same.

2. Description of the Related Art

Liquid crystal display devices have become widespread as monitors forlaptop personal computers and desktop computers.

In such products, a liquid crystal display device is mounted as a liquidcrystal display module including in combination a liquid crystal displaypanel and a light source. A configuration of such liquid crystal displaydevice is described in, for example, Japanese Patent Laid-Open No.264991/1993 and Japanese Patent Laid-Open No. 218914/1995.

SUMMARY OF THE INVENTION

In recent years, commercial products have been diversified in suchproducts as laptop personal computers and desktop computers.

More specifically, under circumstances, in which these commercialproducts are produced in various kinds and small quantity, liquidcrystal display devices cannot but be diversified in configuration.

Meanwhile, reduction of kinds of parts for liquid crystal displaydevices has become a task in order to supply liquid crystal displaydevices stably (first task).

Also, under circumstances in which time taken in using monitors oflaptop personal computers, desktop computers has been increasing, it hasbeen demanded to reduce burdens related to maintenance of thesecommercial products (second task). More specifically, an increase intime taken in using the above-mentioned computer products in use inoffices and personal use has increased burdens on light source units, inparticular, cold-cathode fluorescent tubes used therefor, of liquidcrystal display devices to cause unexpected deterioration of theseparts.

Further, under circumstances, in which computer manufactures haveincreased, it has become important to efficiently supply the abovementioned liquid crystal display devices to these manufactures. Undersuch circumstances, it is essential to reduce probability of breakage ofliquid crystal display devices as much as possible during conveyance ofthe devices to computer manufactures.

However, under circumstances, in which it is promoted to make liquidcrystal display devices thin and to make control devices therefor highin performance, it has become difficult year after year to reduce theabove-mentioned breakage. Also, under circumstances, in which.production of liquid crystal display devices tends to be done in variouskinds and small quantity, there has been increased the possibility thatsupplying of liquid crystal display devices of particular types cannotbut be stopped due to problems of the above-mentioned breakage and soon.

It is a first object of the invention to use types of parts for liquidcrystal display devices in common to stably and flexibly cope withcommercial products of manufactures of computers and televisions whichget various in kind.

It is a second object of the intention to simplify maintenance of liquidcrystal display devices mounted in computers, display monitors therefor,and televisions, and to omit positional adjustment of a light sourceunit and a liquid crystal display panel at the time of maintenance or toprevent particles such as dusts from entering a gap between a liquidcrystal display panel and an optical sheet adjacent thereto.

To solve the above-mentioned problems in a liquid crystal display devicecomprising first, second and third housings the second and thirdhousings of which are detachable from one another, a liquid crystaldisplay panel fixed between the first and second housings, and a lightsource fixed to the third housing, being assembled by overlapping thefirst, second and third housings with one another, the present inventionfixes a timing-converter board fixed to a surface of the third housingopposite to another surface thereof the light source is fixed to, andprovides protrusions being formed on the opposite surface fordetermining a maximum thickness of the liquid crystal display device.The protrusions protect parts of the time-converter board againstbreakage due to external forces applied to the liquid crystal displaydevice.

Also, the protrusions are formed inside a peripheral edge of the liquidcrystal display device.

Also, a light source control circuit is arranged on the opposite sidesurface.

Also, a first fixing means for fixing the first and second housings, anda second fixing means for fixing the second and third housings areprovided, and the first fixing means does not fix the third housing.

Further, a liquid crystal display monitor uses the liquid crystaldisplay device, and the first fixing means is used to fix either of ahousing of the liquid crystal display device, and the first or secondhousings.

The above-mentioned first, second and third housings contain firstmembers (principal plane member, plate) along a principal plane of, forexample, a substrate (for example, a member called a liquid crystaldisplay substrate, or a transparent substrate corresponds thereto)contained in the above-mentioned liquid crystal display panel. In thecase where a peripheral edge of an image display area of a liquidcrystal display device is made small, the first members of the first andsecond housings are occupied at their surfaces by openings, throughwhich a liquid crystal display panel is exposed, to assume aconfiguration of a so-called picture frame. Profiles of these firstmembers are changed in area in the order of, for example the first,second and third housings, and the liquid crystal display device isassembled in such a manner that the profile of the first member of oneof the housings receives therein the profile of the first member of theother of the housings in overlapping manner. Also, at least one of thefirst, second and third housings comprises a second member (side surfacemember, side) projecting from one of surfaces of or a peripheral edge ofthe first member in a thickness direction of the substrate. Inaccordance with use of the liquid crystal display device, the secondmember is in some cases formed integrally in such a manner to surroundat least a part of the one of surfaces of the first member andinterrupting portions such as notches are in some cases provided on atleast the part. The second member also serves as a guide when two of thefirst to third housings are overlapped on one another.

“A thickness (maximum thickness)” of the liquid crystal display devicein the invention is defined as a dimension in a thickness direction ofthe substrate (direction, in which the second member protrudes). Aheight of the protrusion& is defined as a dimension in a thicknessdirection of the substrate. The definition of this configuration will beexplained later with reference to the drawings. In addition, theplurality of protrusions may be provided on the third member to bespaced from one another, or walls formed as the protrusions may beformed on the third member to surround a portion (for example, aportion, on which the above-mentioned parts are mounted) of the firstmember of the third housing.

The invention makes parts of and types of liquid crystal display devicescommon to enable stably and flexibly coping with commercial products ofcomputer makers and televisions makers, which have been increased inkinds. Also, it is possible to simplify maintenance of liquid crystaldisplay devices mounted on computers, display monitors therefor, andtelevisions, and to omit positional adjustment of a light source unitand a liquid crystal display panel at the time of maintenance.Alternatively, in the case where an optical sheet is provided on thesecond housing to be adjacent a liquid crystal display panel, the liquidcrystal display device can be prevented from being deteriorated inoptical characteristics due to entering of dust between the liquidcrystal display panel and the optical sheet, because there is no need toseparate the first housing and the second housing.

These and other objects, features and advantages of the presentinvention will become more apparent from the following description whentaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded, perspective view showing a liquid crystal displaydevice according to the invention (a view as seen from a side of aliquid crystal display panel);

FIG. 2 is an exploded, perspective view showing the liquid crystaldisplay device according to the invention (a view as seen from a backside of the liquid crystal display device, that is, a view as seen froma side opposite to the side of FIG. 1);

FIGS. 3A-3I include assembly drawings FIGS. 3A to 3G, a perspectiveview. FIG. 3H, and a sketch drawing FIG. 3I of the liquid crystaldisplay device according to the invention, as viewed from a right sidesurface (III direction) of FIG. 1.

FIG. 4 is a perspective view showing the liquid crystal display deviceaccording to the invention, as viewed from a left side surface (IVdirection) of FIG. 1;

FIGS. 5A-5D include assembly drawings FIGS. 5A to 5C, a perspective viewFIG. 5D of the liquid crystal display device according to the invention,as viewed from a front side (V direction of FIG. 1;

FIG. 6 is a sketch drawing of the liquid crystal display deviceaccording to the invention, as viewed from a top surface (or the backside of the liquid crystal display device) of FIG. 2;

FIGS. 7A and 7B are illustrations of a first constitution according tothe invention. FIG. 7A shows the case where a light source drive circuitis provided on the liquid crystal display device and FIG. 7B shows thecase where no light source drive circuit is provided;

FIG. 8 illustrates a state, in which the liquid crystal display deviceis packed up at the time of shipping;

FIGS. 9A and 9B are illustrations of a second constitution according tothe invention, FIG. 9A shows the case where a light source drive circuitis removed fro the liquid crystal display device and FIG. 9B shows inenlarged scale a construction shown by a circle of FIG. 9A;

FIGS. 10A-10C shows an example of a monitor making use of the liquidcrystal display device according to the invention, FIG. 10A is a sideview, FIG. 10B is a front view (a view seen from the monitor, that is,from a user's side), and FIG. 10C is a side view showing a state, inwhich the light source unit is removed in the monitor; and

FIG. 11 is a circuit diagram containing a matrix portion and itssurroundings of the liquid crystal display device.

DETAILED DESCRIPTION

An explanation will be given below to an embodiment of the inventionwith reference to the drawings. In addition, parts having the samefunction are designated by the same characters in the drawingsillustrated below, and reiteration of the explanation is omitted.

(Entire Constitution of an Liquid Crystal Display Device)

FIGS. 1 and 2 are exploded, perspective views showing a liquid crystaldisplay device according to the invention.

FIG. 1 is a perspective view from a side of a liquid crystal displaypanel (a front side of the liquid crystal display device relative to auser's visual field), and FIG. 2 is a perspective view from a sideopposite to FIG. 1 (aback side of the liquid crystal display devicerelative to a user's visual field).

In FIG. 1, the reference numeral 1 designates a first housing, 2 secondhousing 2,3 a third housing, 4 a liquid crystal display panel, 5 anoptical sheet (a diffusion film on an optical source side, and a prismfilm on a display panel side), 61 cold-cathode fluorescent tubes, 7 atiming-converter board, 8 a light source control circuit boardconstituting a light source control circuit, 11 an opening (liquidcrystal display window) of the first housing 1, 21 an opening of thesecond housing 13 a hole in the first housing 1, 23 holes in the secondhousing 2, 14 notches (notches bent and fixed) on the first housing 1,24 projections on the second housing, 2, 22 a terrace on the secondhousing 2, 64, 65 frames, 641, 651 rubbers bushes, 43 a flexible printedcircuit board, 62 connectors (high voltage side), 63 connectors (lowvoltage side), 41 a gate drive IC, and 42 a drain drive IC.

In FIG. 2, the reference numeral 31 designates a protrusions provided onthe third housing 3 for protection of parts on the time-converter board7, 32 a surface of the terrace, 321, 331 aprons, 33 an upper surface, 34side surfaces, 341 openings for provision of aprons 331, and 335 anopening for monitoring of brightness of a light source.

The liquid crystal display device is assembled by fixing the liquidcrystal display panel 4 between the first housing 1 and the secondhousing 2, and fixing to the second housing 2 and the third housing 3,to which a light source containing the cold-cathode fluorescent tubes 61(or discharge tubes) is fixed. The second housing 2 and the thirdhousing 3 are detachable. The first housing 1, the second housing 2 andthe third housing 3 are superposed on one another to constitute theliquid crystal display device.

FIGS. 3A 3I include detailed assembly drawings of the above-mentionedliquid crystal display device as viewed from a III direction of FIG. 1and views after assembly, FIG. 4 is a detailed, perspective view showingthe liquid crystal display device after assembly as viewed from a IVdirection of FIG. 1 and FIG. 5A-5D include conceptional assemblydrawings and a view, after assembly, of the liquid crystal displaydevice as viewed from a V direction of FIG. 1. Also, FIG. 6 is anoverhead view of FIG. 2 (a back view of the liquid crystal displayrelative to a user's visual field) after assembly. In addition, it is tobe understood that relative to FIGS. 1 and 2, constitutions in FIGS. 3to 6 are partly deformed for the purpose of explanation. For example,ten cold-cathode fluorescent tubes 61 in FIGS. 1 and 2 are shown as ninein FIGS. 3 to 6.

In FIG. 3A, the reference numeral 12 designates an upper surface of thefirst housing 1, 15 designates a terrace on the first housing 1, and 16designates an underside of the first housing 1.

In FIG. 3B, the reference numerals 411, 421 designate printed circuitboards, and 441, 442 designate LCD substrates.

In FIG. 3C, the reference numeral 25 designates an upper surface(support of the LCD substrates) of the second housing 2, 26 designatesprotrusions, 261 designates openings for receiving the protrusions, and221 designates a terrace.

In FIG. 3E, the reference numeral 642 designates grooves provided on aframe 64 for holding the cold-cathode fluorescent tubes 61, and 643designates screws.

In FIG. 3F, the reference numeral 333 designates a hanger.

In FIG. 3G, the reference numeral 71 designates a timing-converter LSI,72 designates a voltage transformation element (ferrite core), and 73designates a connector (port).

In FIG. 3H, the reference numeral 631 designates a length of cable (lowvoltage side).

In FIG. 3I, MDL designates a liquid crystal display module.

In FIG. 4, the reference numeral 81 designates a voltage transformationelement (ferrite core).

In FIGS. 5A-5D, the reference numeral 74 designates screws for fixingthe timing-converter board 7 to an outside surface of the third housing3, 82 designates screws for fixing the light source control circuitboard 8 to an outside surface of the third housing 3, and 334 designatesscrews.

(Liquid Crystal Display Panel 4)

The liquid crystal display panel 1 comprises, as showing in FIG. 3B, thepaid of substrates 441, 442, a body containing liquid crystal compoundssealed between the substrates, and the drive ICs (integrated circuitelements) 41, 42 for applying electric field to the liquid crystalcompounds to change optical transmissivity in a direction through thesubstrates. These drive ICs are arranged on the printed circuit boards411, 421, which in turn are mounted on a peripheral edge of one 112 ofthe pair of substrates. The liquid crystal compounds sealed between thepair of substrates 441, 442 constitute a so-called liquid crystal layerbetween the substrates, and as the layer is negligibly thin in thicknessas compared with the both substrates, it is not shown.

FIG. 11 is a schematic view showing the liquid crystal display device,that is, a connection diagram containing an equivalent network for adisplay matrix portion and its surrounding network.

Tcon designates a timing-converter circuit, SC designates an imagedisplay region, PX designates a pixel, C_(lc) designates a capacitanceof a liquid crystal layer (cell), C_(s) designates an additionalcapacitance of an pixel, GATE DRV designates a gate signal drivecircuit, GL designates gate signal lines (scanning signal lines),DATA-DRV designates a data signal drive circuit, DL designates datasignal lines (picture signal lines), Vcom designates a common (counter)voltage power source and CL designates a common (Counter) voltage signalline.

The liquid crystal display panel 4 shown in the embodiment is a liquidcrystal display device called an active matrix type, and is known as onehaving, for example, an equivalent network shown in FIG. 11. As shown inFIG. 11, the liquid crystal display device of this type have switchingelements TFT on respective pixels PX (one of which is shown in an areaenclosed by broken lines) arranged two-dimensionally in an image displayarea (a so-called screen) SC, and at least a pair of electrodes (formingof capacitance C_(LC) with the liquid crystal layer therebetween) forapplication of electric field to the liquid crystal layer. In the liquidcrystal display device according to the embodiment, the above-mentionedswitching elements TFT are represented by symbols for field-effecttransistors, and may be replaced by diodes or the like.

The gate signal lines GL are connected to gate electrodes of symbols forfield-effect transistors, to which signals from the gate signal drivecircuit GATE-DRV are supplied. The gate signal lines GL are arranged inplural in parallel (on, for example, the substrate 112 and connected togate electrodes of the switching elements TFT for the respective pixelsPX arranged along the respective gate signal lines GL.

Meanwhile, each of electric paths opened and closed by the switchingelements TFT is connected at one end thereof to one of a pair ofelectrodes (called pixel electrodes), for which form capacitance C_(LC)with the above-mentioned liquid crystal layer therebetween, andconnected at the other end thereof to the data signal lines DL. The datasignal lines DL are arranged in plural in parallel on, for example, thesubstrate 442, and connected to the above mentioned other ends of theswitching elements TFT for the respective pixels PX arranged along therespective data signal lines DL. At the above-mentioned other ends ofthe switching elements TFT are supplied with signals from the datasignal drive circuit DATA-DRV. The above-mentioned one, ends of theswitching elements TFT may be conveniently called source electrodes, andthe other ends called drain electrodes, irrespective of functionsthereof. Therefore, the data signal drive circuit DATA-DRV is called“drain signal drive circuit”.

The data signal lines DL and the gate signal lines GL extend indirections, in which they intersect each other, and are electricallyseparated from each other above and below an insulating film (forexample, a gate insulating film of the above-mentioned field-effecttransistors) on the substrate 442.

In the respective pixels PX shown in FIG. 11, the other (called counterelectrode or common electrode) of the pair of electrodes, which formcapacitance C_(LC) with the liquid crystal layer therebetween, isapplied with a predetermined voltage through the counter voltage signline CL from the voltage power source Vcom. Also, the additionalcapacitance C_(s) is formed in order to suppress fluctuation ofpotential difference between the electrodes, which form capacitanceC_(LC) with the liquid crystal layer therebetween, while the switchingelements TFT are closed. The additional capacitance C_(s) is constitutedby, for example, having the above-mentioned pixel electrode and thecounter electrode facing each other with a dielectric (theabove-mentioned gate insulating film or the like) except the liquidcrystal layer. With ones called a TN type (twisted nematic) among liquidcrystal display devices, the pixel electrode and the counter electrodeare frequently arranged to face each other with the liquid crystal layerinterposed therebetween, and with ones called a IPS type (enplaneswitching type) or a FFS type (fringe field type), the pixel electrodeand the counter electrode are frequently arranged on the same substrate.With the TN type, pixel electrodes are provided separately every pixelPX on, for example, the substrate 442, while counter electrodes are insome case provided, which is large to face pixel electrodes of aplurality of pixels PX disposed in the image display area SC on thesubstrate 441.

With a liquid crystal display device of active matrix type, switchingelements TFT of a plurality of pixels PX along the respective gatesignal lines GL are selectively opened every gate signal line GL tosupply data signals to the pixels disposed along the respective gatesignal lines GL in a time-divisional manner. A circuit for controllingthis is called the timing-converter circuit Tcon. Such timing-convertercircuit Tcon generates clock signals for e.g. the above-mentionedtime-divisional control, and supplies a liquid crystal drive voltageapplied to the liquid crystal layer, which corresponds to individualpixels PX. A circuit having a function similar to this is used inpassive matrix type liquid crystal display devices (typified by STN(super twisted nematic). Accordingly, the time-converter circuit Tcon isestimated as a liquid crystal drive control and power source circuit.

The timing-converter circuit Tcon is formed on the timing-converterboard 7 (printed board) shown in FIGS. 1 to 6 to be disposed on a backsurface (an upper surface 33 shown in FIG. 2) of the third housing 3 asviewed from a user of the liquid crystal display device. As shown inFIGS. 3 and 6, the timing-converter board 7 mounts thereon the voltagetransformation element 72 made of ferrite core or the like in additionto the timing-converter LSI 71. While other elements are formed on thetiming-converter board 7, they are omitted from the drawings for thesimplicity of explanation.

As described above, the timing-converter circuit Tcon not only generatessignals for image display control, but also supplies data signal voltageapplied to the liquid crystal layer. The liquid crystal display deviceis supplied with a power source voltage of, for example, 12 V (even whenAC voltage of 100 V is supplied from an external power source, it isonce converted in a predetermined power source voltage value). Incontrast, the drive ICs connected to the gate signal lines GL and thedata signal lines DL have voltage of 3 V to 5 V. On the other hand,voltage applied to the liquid crystal layer by the pixel electrodes inthe individual pixels PX ranges, for example, from 5 V to 10 V dependingupon the kind of liquid crystal compounds used. Further, to avoidpolarization of the liquid crystal layer during control thereof, it isnecessary to reverse polarity relatives to electric potential of thecounter electrodes. Accordingly, it is requested that supplying ofvoltage to the pixel electrodes realize voltage fluctuation in the rangeof two times voltage applied the liquid crystal layer, for example, 10 Vto 20 V. Therefore, it is essential to mount the voltage transformationelement 72 on the timing-converter board 7 in order to general voltagesignals, which are different in width of fluctuation by uses, from apredetermined voltage supplied to the timing-converter substrate. Suchrequest is the same with a liquid crystal drive control and power sourcecircuit in passive matrix type liquid crystal display devices

In a liquid crystal display device of active matrix type, the gatesignal drive circuit GATE-DRV shown in FIG. 11 contains the plurality ofgate drive ICs 41 (shown in FIGS. 1, 3 and 4. The timing-converter board7 and these groups of drive IC's are connected to each other by theflexible printed circuit board 43. A circuit pattern generated on theflexible printed circuit board 43 is connected at one end thereof to acircuit pattern generated on one end of a printed circuit board 412mounting the data drive IC's 42, and a terminal provided on the otherend thereof is inserted into the connector (port) 73 provided on thetiming-converter board 7 to connect the both circuit patterns to eachother.

The timing-converter board 7 supplies, through the flexible printedcircuit board 43, clock signals, drive voltage of the date drive IC's 41and so on to the gate signal drive circuit GATE-DRV, and supplies clocksignals, drive voltage of the data drive IC's 42, voltage applied to theliquid crystal layer and so on to the data signal drive circuitDATA-DRV. The gate drive IC's 41 constituting the gate signal drivecircuit GATE-DRV are mounted on a printed circuit board 411, and receivevoltages and signals from the timing-converter board 7 owing toconnection of the both circuit patterns to each other by means ofjoiners (not shown) provided between the printed circuit board 411 andthe printed circuit board 412. An arrangement similar to the above oneis found in passive matrix type 1 liquid crystal display devices, so,for example, the gate drive ICs 41 are replaced by common electrodedrive IC's, and the data drive ICs 42 are replaced by segment driveICs).

(Storage of the Liquid Crystal Display Panel 4)

The above-mentioned liquid crystal display panel 4 is contained betweenthe first housing 1 and the second housing 2 shown in FIGS. 1 to 3.

The image display are SC not shown but diagrammatically shown in FIG. 11is formed on an upper surface of the liquid crystal display panel 4shown in FIG. 1. The first housing 1 has the opening 11 contacting withthe upper surface, through which opening a user of the liquid crystaldisplay device sees the image display area SC. A surface of the firsthousing 1 having therein the opening 11 is formed by a sheet materialof, for example, metal or the like, which has the upper surface 12facing a side of a user of the liquid crystal display devices and thesurface (underside) 16 to opposite to the upper surface, as shown inFIG. 3A. The liquid crystal display panel 4 shown in FIG. 1 is fixed tothe first housing 1 with a peripheral edge of its upper surfacecontacting with the underside 16.

The underside (upper surface in FIG. 2) of the liquid crystal displaypanel 4 shown in FIG. 1 is fixed such that its peripheral edge contactswith a recess 25 on the upper surface of the second housing 2 shown inFIG. 3C. Although not shown in FIG. 3C, the recess 25 on the uppersurface is provided with an opening, which corresponds to the imagedisplay area SC in the liquid crystal display panel 4.

In this manner, the first housing 1 and the second housing 2 are fixedin a state, in which the peripheral portions on the upper surface of andon the underside of the liquid crystal display panel 4 are contactedwith the first housing 1 and the second housing 2, respectively. Eitherof the first housing 1 and the second housing 2 is formed with a sidesurface, which extends in a direction, along which its peripheral edgeintersects the upper surface or the underside of the liquid crystaldisplay panel 4. As shown in FIGS. 1 and 3A, rectangular-shaped notches14 are formed on lower portions of side surfaces of the first housing 1.Also, holes are provided at two locations on III- and V-sides,respectively, of these side surfaces in FIG. 1. Meanwhile, as shown inFIGS. 1 and 3B, protrusions 24 are formed on lower portions of sidesurfaces of the second housing 2. Also, holes 23 are provided at twolocations on III-and V-sides, respectively, of these side surfaces inFIG. 1.

The liquid crystal display panel 1 is received between the first housingand the second housing 2 in a state, in which the second housing 2 iscovered by side surfaces of the first housing 1 when the both housingsare put together. The holes 13 in the first housing 1 and the holes 23in the second housing 2 are formed so as to be substantially aligned inposition when the liquid crystal display panel 4 is held between thesehousings. Threads are formed on inner walls of at least one of the holes13 and the holes 23. First, screws are passed through the correspondingholes 23 from the four holes 13 (two on the III-side and two on theV-side in FIG. 1) on the side surfaces of the first housing 1 to looselyfix the first housing 1 and the second housing 2 to each other.

At this time, the notches 14 on the side surfaces of the first housing 1come near the protrusions 24 provided on the lower portions of the sidesurfaces of the second housing 2 (see FIGS. 1, 3C and 5B). Therespective notches 14 are pushed and bent below the side surfaces of thesecond housing 2 (in other words, inside the first housing 1) in such amanner as to have rectangular, upper sides of the notches 14 (see FIGS.1, 3A and 5A) abutting against the lower portions (on which theprotrusions are not formed) of the protrusions 24 on the side surfacesof the second housing 2. Thereby, the first housing 1 and the secondhousing 2 are fixed to each other. FIG. 6 shows the first housing 1 asbeing positioned outermost as a profile 1 of its side surfaces and thesecond housing 2 as being positioned adjacent to the profile 1 of thefirst housing 1 as a profile 2 (a portion thereof partly covered by theterrace on the first housing 1 (described later) in an upper area of thedrawing being indicated by broken line) of its side surfaces. As shownin FIG. 6, the notches 14 are bent whereby the first housing 1 assumessuch a configuration that the notches hold undersides of the sidesurfaces of the second housing 2. In this manner, for example, JapanesePatient Laid-Open No. 199180/1995 discloses a configuration, in whichnotches 14 (or pawls) are formed on side surfaces of one of housings andare pushed into recesses formed on those side surfaces of the other ofthe housings, which contact with the side surfaces of the one of thehousings, to fix the two housings. Of course, the notches 14 on the sidesurfaces of the first housing 1 may be replaced by holes and the sidesurfaces of the second housing 2 may be extended downward to permitthreaded holes to be formed on the side surfaces to be conformed to theholes on the side surfaces of the first housing.

As shown in FIGS. 1, 3C and 5B, upwardly extending protrusions 26 areformed on upper portions of the side surfaces of the second housing 2.The protrusions 26 are provided by forming cuts partially on the sheetmaterial on the side surfaces and bending the same upward. Accordingly,openings 261 appear on the upper portions of the side surfacescorresponding to the protrusions 26. The protrusions 26 serve as a guidewhen the second housing 2 is inserted into a space defined by the sidesurfaces of the first housing 1, and are formed so as to contact withthe underside 16 of the first housing 1 (see FIGS. 3A and 5A) at thetime when the liquid crystal display panel 4 is received between thehousings. Therefore, even if forces tending to push the housings towardeach other were applied, they would be buffered by the protrusions 26and the underside 16 of the first housing 1 before being applied to theliquid crystal display panel 4, whereby in particular, the glasssubstrate of the liquid crystal display panel is prevented from beingbroken.

As shown in FIGS. 3C and 5B, the second housing 2 is formed withterraces 22, 221, which extend inside from the side surfaces, as well aswith the upper surface 25 having the recess holding the liquid crystaldisplay panel 4. The terrace 22 hides below the upper surface 25 of thesecond housing 2 in FIG. 1 but can be seen in FIG. 2. Also, as shown inFIG. 5B, the terrace 22 is formed on that portion of the side along thedata drive ICs 42, on which the protrusions 24 are formed. Formedbetween the terraces 22, 221 and the underside (back surface) of theupper surface 25 is a gap, into which an end of the optical sheet 5shown in FIG. 3D is inserted to be fixed. The optical sheet 5 is fixedin the order of, for example, the prism sheet and diffusion sheet from aside of the liquid crystal display panel 4. The diffusion sheet may bereplaced by a diffusion plate, which is provided by applying dotprinting to an acrylic plate, in which case the recess portion on theupper surface 25 is preferably formed by a separate member and an edgeof the upper surface 25 surrounding the recess is fitted onto aperipheral edge of the member. With such arrangement, the diffusionplate is surely fixed to the second housing 2 upon securing of the firsthousing 1 and the second housing 2. The optical sheet may be replaced bya constitution composed of a first prism sheet, a first diffusion sheet,a second diffusion sheet, and a second prism sheet for the liquidcrystal display panel 4 in accordance with use of the liquid crystaldisplay device and specifications of an optical source unit describedlater.

<Assembly of the Optical Unit (Securing Manner Thereof to the ThirdHousing 3)>

As shown in FIGS. 1, 2 and 3E, the third housing 3 is composed of theupper surface 33 projecting on a back side as viewed from a user of theliquid crystal display device, side surfaces 34 joined to two oppositesides at ends of the upper surface, and terraces 32 joined to ends ofthe respective side surfaces to extend on a plane along the uppersurface 33. As shown in FIGS. 3A-3I, assuming that a side of a user ofthe liquid crystal display device is disposed on an upper portion of thedrawing, the third housing 3 has a cross sectional shape “downwardlyconcave”. Also, as apparent from FIGS. 1 and 5C, the downwardly concave,cross sectional shape appears along a direction, in which the gate driveICs 41 are arranged, but does not appear along a direction, in which thegate drive ICs 42 are arranged.

In this embodiment, the downwardly concave shape of the third housing 3is made use of to fix the plurality of cold-cathode fluorescent tubes61, which constitute light source units of the liquid crystal displaydevice. Supplied at one ends with a higher voltage than at the otherends, the cold-cathode fluorescent tubes 61 is lit. The one ends of thecold-cathode fluorescent tubes 61 are called high voltage sides (hotsides), and the other ends are called low voltage sides (cold sides). InFIG. 1, portions near the high voltage ends of the cold cathodefluorescent tubes 61 are fitted into grooves 652 provided on the frame65, and rubber bushes 651 are inserted into the grooves 652 to be fixedto the frame 65. Likewise, portions near the low voltage ends of thecold-cathode fluorescent tubes 61 are fitted into the grooves, 642provided on the frame 64, and rubber bushes 641 are inserted into thegrooves to be fixed to the frame 64. The frames 64, 65 fixing theretothe both ends of the cold-cathode fluorescent tubes 61 are fixed to andcontacted with the upper surface 33 and side surfaces 34 on the thirdhousing 3 FIG. 3E is a view illustrating assembly as viewed from the lowvoltage sides of the cold-cathode fluorescent tubes 61. screws 643 arepassed through holes (not shown) formed on both ends of the frame 64,and tip ends of the screws are inserted into and fixed to screw holes(not shown) provided on the upper surface 33 shown in FIG. 3F (back sideof the upper surface 33 as viewed from FIG. 2). The frame 65 on the highvoltage sides of the cold-cathode fluorescent tubes 61 is fixed to thethird housing 3 by way of similar screws, but an illustration thereof isomitted. The low voltage terminals of the cold-cathode fluorescent tubes61 project from the frame 64, and the high voltage terminals projectfrom the frame 65. Connectors 63 are connected to the low voltageterminals, and connectors 62 are connected to the high voltageterminals. In the present embodiment, the connectors 63 connecting inparallel to the plurality of terminals of the cold cathode fluorescenttubes 61 are used in order that a terminal voltage on the low voltageside be made a reference voltage in the third housing 3 (ground voltagein the case where the third housing 3 itself is to be kept at groundpotential). FIG. 3H is a perspective view after assembly of the first tothird housings, which shows a parallel connection to lengths of cable(lead) 631 passing through central portions of the connectors 63 in theform of frame shown by broken lines. Meanwhile, the connectors 62 havingseparate leads for every terminal are used for the high voltageterminals of the cold-cathode fluorescent tubes 61. As shown in FIG. 1and perspective views as viewed in a IV direction after assembly of thefirst to third housings, four of the connectors 62 present such anexternal appearance that they were connected to two of the cold-cathodefluorescent tubes 61. However, internal wiring is not one for conductionbetween two of the cold-cathode fluorescent tubes 61. This is because ofconsideration in making lengths of voltage supply paths between the highvoltage terminals of the respective cold-cathode fluorescent tubes 61and voltage transformation elements 81, described later, for supplyingof voltage to the respective terminals, uniform. The above-mentionedconnection of the connectors 62, 63 leads to completion of a lightsource unit of the so-called type built-in, immediately below abacklight panel, in which the plurality of the cold-cathode fluorescenttubes 61 are arranged opposite to the liquid crystal display panel 4. Inaddition, reflective sheets (not shown) are applied on surfaces on thosesides of upper surface 33 and the side surfaces 34 of the third housing3, to which the built-in frames 64, 65 are fixed, whereby light radiatedon the surfaces from the respective cold-cathode fluorescent tubes 61 isreflected on the liquid crystal display panel 4 to enhance luminance ofthe image display area SC.

The timing-converter board 7 shown in FIGS. 1 and 3G and the lightsource control circuit board 8 (printed circuit board) shown in FIG. 1are mounted on the upper surface 33 (a side opposite to that side, onwhich the built-in frames 64, 65 for the cold-cathode fluorescent tubes61 are fixed) of the third housing 3. These boards are formed by cuttingportions, of a sheet material, which constitutes the upper surface 33,raising the same above the upper surface 33 (back side as viewed from auser of the liquid crystal display device), and further securely fittingperipheral edges of the same onto hangers 333, which are formed in anangle fashion. The timing-converter board 7 are required to be disposedat corners of the upper surface 33 for the purpose of supplying signalsand voltage to the gate drive ICs 41 and the gate drive IC's 42.Therefore, as shown in FIGS. 2, 3F and 6, portions of the side surfaces34 of the third housing 3 are cut from the upper surface 33 side to formaprons 331 conformed to a height of the upper surface 33. Thetiming-converter board 7 is fixed to screw holes 334 provided on theaprons by means of screws 74. Meanwhile, the light source controlcircuit board 8 is also fixed to the upper surface 33 by means of screws82.

The light source control circuit board 8 in this embodiment is formedwith an inverter circuit (dinner circuit) for controlling lighting ofthe cold-cathode fluorescent tubes 61, and a power source circuit, whichis controlled by the former to supply voltage to the high voltageterminals of the respective cold-cathode fluorescent tubes 61. As thetechnique for using an inverter circuit to stabilize lighting of thecold-cathode fluorescent tubes 61 has already become widespread, adetailed explanation thereof is omitted herein. Voltage supplied to thehigh voltage terminals of the respective cold-cathode fluorescent tubes61 is high, for example, 600 V, 6 mA relative to drive voltages for notonly the inverter circuit but also the dinner circuit. In contrast,power source voltage supplied to light source control circuit board 8 islow like that on the timing converter board 7. Also, it is desired thatvoltage supply paths for supplying such high voltage to the high voltageterminals of the respective cold-cathode fluorescent tubes 61 be madesmaller, and it is requested in giving uniform brightness to the imagedisplay area SC in the liquid crystal display panel 4 that voltagesupply paths between the cold-cathode fluorescent tubes 61 be madeuniform in length especially in a light source unit, which uses theplurality of cold-cathode fluorescent tubes 61. Therefore, the voltagetransformation elements 81 for supplying voltage to the high voltageterminals of the respective cold-cathode fluorescent tubes 61 aremounted on the light source control circuit board 8 disposed on theupper surface of the third housing 3, and in the case where theplurality of cold-cathode fluorescent tubes 61 are provided in parallelas in the embodiment, the voltage transformation elements 81 will bedisposed along the arrangement of the cold-cathode fluorescent tubes 61.

Such request for the specification of the light source control circuitboard 8 is the same not only for a light source unit of theabove-mentioned type built-in immediately below a backlight panel, butalso for a configuration (light-transmission plate type light sourceunit), in which discharge tubes such as the cold-cathode fluorescenttubes 61 are arranged in a position offset from a lower portion of theimage display area SC in the liquid crystal display panel 4, and alight-transmission plate for transmitting light is disposed in the lowerportion of the image display area SC so that light from the dischargetubes is conducted via the light transmission plate to the image displayarea SC in the liquid crystal display panel 4. The reason for this isthat in this configuration high voltage as compared with that for theabove-mentioned other drive circuits must be supplied to one ends of thedischarge tubes.

Accordingly, configurations of a circuit pattern in the light sourcecontrol circuit board 8 and of the connectors 62 on the high voltageside, connected to the board are designed taking account of theserequests.

In contrast to that wiring on the high voltage side of the cold-cathodefluorescent tubes 61, which is restricted with respect to lengths of thevoltage supply paths, wiring on the low voltage side has freedom inconfiguration. For example, as shown in FIG. 6, the cable 631 may beextended to the light source control circuit board 8 across the uppersurface 33 of the third housing 3 from the low voltage terminals of thecold-cathode fluorescent tubes.

In addition, as shown in FIG. 6, the upper surface 33 of the thirdhousing 3 contains a so-called vacant space where the timing-converterboard 7 and the light source control circuit board 8 are not disposed.Such vacant space is suitable for mounting of optional circuits bymakers, which incorporate liquid crystal display devices into setproducts such as personal computers, liquid crystal display monitors ortelevisions. Also, an opening 335 formed centrally of the upper surface33 serves as a measurement window of a light receiving element formeasuring luminance of the cold-cathode fluorescent tubes. In the casewhere a luminance monitor circuit of the light source unit is mounted inthe vacant space on the upper surface 33 of the third housing 3, theliquid crystal display panel can be stably maintained in brightness bymeasuring emission luminance of the light source unit through theopening 335, and performing feed-back of the result to a control circuiton the light source control circuit board 8. (Assembly of the LiquidCrystal Display Device (fixing of the third housing 3 to the secondhousing 2))

As described above, the third housing 3, into which the light sourceunit is assembled and to which the timing converter board 7 and thelight source control circuit board 8 are fixed, is fixed to the secondhousing 2. Such fixed configuration is shown in FIG. 3( h), which is aperspective view as viewed from a III direction of FIG. 1, and shown inFIG. 4, which is a perspective view as viewed from a IV direction ofFIG. 1, and further shown in FIG. 5D, which is a perspective view asviewed from a V direction of FIG. 1.

As shown at a left end of FIG. 3H, the terrace 32 formed at one end ofthe third housing 3 and the terrace 22 extended from inside the sidesurface of the second housing 2 are fixed to each other by screws 322.Locations for such fixing are three as shown in FIGS. 5A-5D. The screws322 are set in length so as not to extend through the terrace 22 toproject much from the upper surface thereof.

Meanwhile, as shown on a right side of FIG. 3H, the terrace 221 extendedfrom inside the side surface of the second housing 2 and the terrace 15extended from inside the side surface of the first housing 1 define arecess. Fitted into this recess is the terrace 32 formed at the otherend of the third housing 3. The third housing 3 is fixed to the secondhousing 2 by first fitting the terrace 32 formed at the other end of thethird housing 3 into the recess, then putting the terrace 32 formed atthe one end of the third housing 3 and the terrace 22 of the secondhousing 2 together to fix them by the screws 3.2.2.

Instead of forming the recess by the terrace 15 on the right side ofFIG. 3H, screw holes may be provided in the terrace 221 of the secondhousing and the terrace 32 at the other end of the third housing 3 maybe fixed by screws. This configuration makes the first housing simple indesign.

Meanwhile, in the case of screwing the terrace 32 to the terraces 22,221, the following should be taken care of. In the case where an opticalsheet is somewhat large in size, tip ends of the screws projected fromupper surfaces of the terraces 22, 221 press ends of the optical sheet.Such pressing causes the possibility of imparting an unexpectedpolarized component to light incident on the liquid crystal displaypanel 4 from the light source unit. To avoid this, there is recommendeda configuration, in which the terrace 32 formed at the other end of thethird housing 3 is fitted into the recess. Also, in the embodiment, aposition where the terrace 32 at the one end of the third housing 3 isscrewed to the terrace 22 of the second housing 2 is set near an innerwall on the side surface of the second housing 2 distant from the imagedisplay area SC in the liquid crystal display panel 4. Further, theposition of screwing is provided on a side where the gate drive ICs 42are arranged. The reason for this is that a position, which meets atleast one of these conditions, makes a dead space (there is nopossibility that the optical sheet is extended to this position)relative to the position of the optical sheet even taking account oferrors in design. Meanwhile, in the embodiment, as shown in FIGS. 5A and5B, the protrusions 24 are provided on the lower portion of the sidesurface of the second housing 2, and notches 14 formed on the lowerportion of the side surface of the second housing 2, and notches formedon the lower portion of the side surface of the first housing 1 arefitted right and left of the protrusions. Therefore, the terrace 32cannot be screwed to the terrace 22 in a position near the side surfaceof the second housing 2 where the notches 14 are fitted. Hereupon, asshown in a lower portion of FIG. 6, the terrace 22, on an end of whichthe protrusions 24 are formed, is used for screwing. This is because thenotches 14 are not fitted on the underside of the terrace 22. Also, theentire terrace 32 of the third housing 3 is not extended to the innerwall on the side surface of the second housing 2, but a portion used forthe above-mentioned screwing is extended as the terrace 321 to the innerwall on the side surface of the second housing 2 and ends thereof areused for screwing as shown in FIGS. 2 and 6.

In addition to the above-mentioned screwing and fitting into the recess,the terrace 32 of the third housing 3 and the terraces 22, 221 of thesecond housing 2 may be fixed to one another by providing clips (notshown) on, for example, the terrace 22 of the second housing 2 andhaving them interposing therebetween the aprons 321, which project fromthe terrace 32 of the third housing 3. The clips may be installed byfixing elastic clip members to the terrace 22 by way of screws,soldering or welding, but in the case where the second housing 2 isformed from elastic metals, resins or the like, it may be partiallyformed with notches and portions thereof may be raised toward thecontact surfaces of the aprons 321. In this case, the aprons 321 arefixed by the use of righting forces of the notch portions of the terrace22.

The third housing 3 is fixed to the second housing 2 to complete theliquid crystal display device according to the embodiment. FIG. 3I showsan external appearance of a liquid crystal display module MDL as viewedfrom a III direction of FIG. 1. As compared with the perspective viewshown in FIG. 3H, the external appearance becomes neat and clear. Theseliquid crystal display devices are also called a liquid crystal displaymodule, and are actually incorporated into housings of personalcomputers, liquid crystal display monitors or televisions to be sold toconsumers. (Setting of the Protrusions 31 on the Upper Surface of theThird Housing 3)

Although not conspicuous in the external appearance shown in FIG. 3I, anupper end of the voltage transformation element 2 mounted on thetiming-converter board 7 actually projects in many cases from theunderside of the side surface of the first housing 1. Also, when seen inthe IV direction in FIG. 1, that is, from a side where the light sourcecontrol circuit board 8 is mounted, upper ends of the voltagetransformation elements 81 mounted on the light source control circuitboard 8 project from the first side surface as shown in the perspectiveview shown in FIG. 4.

When elements fixed to the housings assembled in this manner project,there is caused the possibility that these elements may be broken at thetime of mounting of the liquid crystal display devices onto set productssuch as personal computers, liquid crystal display monitors ortelevisions. Also, there is caused a similar possibility at the time ofshipment of the liquid crystal display devices to makers of theabove-mentioned set products.

In the present invention, the protrusions 31 are provided on the uppersurface 33 (back side as viewed from a user of the liquid crystaldisplay device) of the third housing 3 in order to protect elements(electronic parts and so on) fixed to the housings, which constitute theliquid crystal display device, from the above-mentioned breakage. Thereason for provision of the protrusions 31 on the third housing 3 is asfollows.

As described above, the third housing 3 is provided with the lightsource unit. Meanwhile, the first housing 1 and the second housing 2grasp the liquid crystal display panel 4 by peripheral edges of theupper and lower surfaces thereof to receive the liquid crystal displaypanel 4 therebetween as described above. One of the upper and lowersurfaces of the liquid crystal display panel 4 therebetween as describedabove. One of the upper and lower surfaces of the liquid crystal displaypanel 4 must have light from the light source unit being incident upon aliquid crystal layer provided therein, and the other of the upper andlower surfaces must display an image, which is generated by modulationof the light at the liquid crystal layer, to a user of the liquidcrystal display device. Because of this, the first housing 1 and thesecond housing 2 are formed with openings (for example, the opening 11of the first housing 1 shown in FIG. 3A) along the surface (the mainsurface of one of the substrates 441, 442 contained in the panel) of theliquid crystal display panel 4. In contrast, it is not necessary to formany opening on a member (an upper portion of the upper surface 33 inFIG. 3I) of the third housing 3, which holds the light source unit.Therefore, mounting of the timing-converter board 7 and the light sourcecontrol circuit board 8 on the member is desired in stably fixing theseboards to the liquid crystal display device. Accordingly, electriccircuit elements being protected by the protrusions 31 are fixed to thetiming-converter board 7 and the light source control circuit board 8,so that they are naturally disposed on the upper surface 33 of the thirdhousing 3.

Also, since the first housing 1 and the second housing 2 protect aperipheral edge of the liquid crystal display panel as well as the driveICs, they become large in area along the surfaces of the liquid crystaldisplay panel 4. In contrast, the light source unit suffices to supplylight to the image display area SC in the liquid crystal display panel4, and so its area along the surfaces of the liquid crystal displaypanel 4 may suffice to correspond to the mage display area SC or enlargethe surrounding a little (needs not be enlarged to a side of the driveECs). As apparent from this, the first housing 1 and the second housing2 are formed to be larger than the third housing 3 as viewed in adirection (for example, from a viewpoint in FIG. 6) perpendicular to thesurface of the liquid crystal display panel 4. In other words, the uppersurface 33, the side surfaces 34 and the terrace 32, which constitutethe third housing 3, are contained in the respective outer frames of thefirst housing 1 and the second housing 2.

Therefore, the provision of the protrusions 31 or their equivalent onthe third housing 3 rather than on the first housing 1 and the secondhousing 2 is effective in protecting the above-mentioned electriccircuit elements arranged on the upper surface 33 of the third housing3.

FIGS. 7A and 7B are illustrations of a first constitution according tothe invention, FIG. 7A showing the case where the liquid crystal displaydevice shown in FIG. 5D is reversed up and down. In the followingexplanation, a dimension of the liquid crystal display device along avertical direction in FIG. 7 is represented as “thickness” or “height,”and a dimension of the liquid crystal display device along a directionlaterally across FIG. 7 is represented as “width” or “area”.

Seeing FIG. 7A on the assumption that the protrusions 31 are not presenton the upper surface 33 of the third housing 3, it is focused that athickness h₁ of the liquid crystal display device is determined by thevoltage transformation elements 81 on the light source control circuitboard 8. In the case where the timing-converter board 7 and the lightsource control circuit board 8 are not provided on the upper surface 33of the third housing 3, the thickness of the liquid crystal displaydevice is determined by a difference h₁ in level between the uppersurface 12 of the first housing 1 (see FIG. 3A) and the upper surface 22of the third housing 3 (see FIG. 3F) (the hangers 333 are neglected).Therefore, the protrusions 31 are provided on the upper surface 33 ofthe third housing 3, and their height h₆ is determined so as to satisfythe relationship h₆>(h₁ h₂). As a result, although the thickness(maximum thickness) of the liquid crystal display device is increased toh₁ (however, h₁>h₁), a work of mounting the liquid crystal displaydevice on set products is not adversely affected because a positionwhere the protrusions 33 are formed is set back from the peripheral edgeof the liquid crystal display device.

In some cases, makers of set products provide light source drivecircuits on bodies of such set products as personal computers and thelike to make use of a liquid crystal display device in a state, in whichthe light source control circuit board 8 is not mounted on the liquidcrystal display device. In this case, as apparent from FIG. 7A, fromwhich the light source control circuit board 8 and all elements mountedon the board are all removed, the thickness h₂ of the liquid crystaldisplay device except for the protrusions 31 is determined by thevoltage transformation element 72 on the timing-converter board 7. Asapparent from FIG. 7A, the protrusions 31 having a thickness of h₆ ishigher than necessary to protect the electric circuit elements on thetiming-converter board 7, and rather causes the possibility ofinterfering with a work, in which the liquid crystal display device isassembled into set products.

In this case, only a member of the third housing 3 is prepared which isdifferent from that shown in FIG. 7A. The third housing 3 shown in FIG.7B is such that the protrusions 31 have a thickness h₆₂ (however,h₆₂>(h₂−h₂) is met). Therefore, the entire liquid crystal displaydevice, on which the light source control circuit board 8 is notmounted, has a thickness h₂ (maximum thickness) smaller than h₁.

As apparent from the above explanation, there is involved thepossibility that depending upon whether a light source control circuitis mounted on a liquid crystal display device mounting thereon a liquidcrystal display panel 4 having the same dimension, a housing of thedevice is substantially varied in size. In the invention, the thirdhousing 3 having the protrusions 31, which are different only in height,is prepared to accommodate variation of the liquid crystal displaydevice, but the following problems arise in the case where protrusionsor the like are provided on the side surfaces of the first housing 1 andthe second housing 2 to protect the above-mentioned electric circuitelements.

One of the problems is that lines for manufacture of two kinds of liquidcrystal display device products, which are different from each otheronly with respect to the presence of a light source control circuit,must be provided separately from mounting of a liquid crystal displaypanel 4. Since the first housing 1 and the second housing 2 are bothmembers serving to grasp the liquid crystal display panel 4, assembly onthe same line is complex to lower productive efficiency in the casewhere either of the housing is varied in configuration.

Another one of the problems is that in the case where assembly of thefirst housing 1 and the second housing 2 of one of the two kinds ofliquid crystal display device products is delayed, or failure generates,production itself of that kind of liquid crystal display device productswill be delayed.

A configuration of the third housing 3 copes with manufacture of twokinds of liquid crystal display device products as in the invention, andthen the process of grasping of the liquid crystal display panel 4 withthe first housing 1 and the second housing 2 and the intermediateproducts in the process are made common to the two kinds of liquidcrystal display device products.

Further, the invention has the following advantages in conveyance ofliquid crystal display device products.

These will be explained using an illustration of FIG. 8 showing acondition of packaging at the time of shipment of liquid crystal displaydevices (also, called a liquid crystal display module).

In FIG. 8, BX denotes a cardboard box for conveyance (for example,decorative box), PKG denotes a packing (cushioning) material, VYNdenotes vinyl bags, and MDL denotes liquid crystal display modules (theabove-mentioned liquid crystal display device products). The liquidcrystal display modules MDL shown employ the invention in which theprotrusions 31 for protection of circuit elements are provided on thethird housing 3 (a plurality of the liquid crystal display device shownin FIG. 7A are shown in FIG. 8 while being reduced in size and turned 90degrees.

A cushioning material such as urethane foam or the like is used as thepacking material PKG on inner walls of the cardboard box BX forconveyance. Every one of the liquid crystal display modules MDL iscontained in the vinyl bag VYN to be received in the cardboard box forconveyance BX. The packing material PKG is also inserted between theliquid crystal display modules MDL, but cardboard for cardboard boxes isfrequently used in place of the packing material.

In such packaging configuration, the protrusions 31 formed on therespective liquid crystal display modules MDL (or the third housing 3)inhibit flexure of the packing material PKG inserted therebetween toprevent the flexed packing material PKG from pressing and breakingelectric circuit elements mounted on the respective liquid crystaldisplay modules MDL.

As described above, an area of the third housing 3 extending along themain surfaces of the substrates 441, 442 (also, called a liquid crystaldisplay board) contained in the liquid crystal display panel 4 issmaller than those of the first housing 1 and the second housing 2.Therefore, the provision of the protrusions 31 on the third housing 3presents an advantage that the protrusions 31 were provided on the firsthousing 1 and the second housing 2, location of the protrusions 31 wouldbe distant from the electric circuit elements. The packing material PKGwould flex by an amount of the distance between the protrusions 31 andthe electric circuit elements. In view of this, it is apparent thatpossible breakage of the electric circuit elements can be surelyprevented by the provision of the protrusions 31 on the third housing 3.

In addition, the voltage transformation elements 72, 81 mounted on thetiming-converter board 7 and the light source control circuit board 8are constituted to include parts such as ferrite core and so on. Whiledepending upon function of the voltage transformation, the voltagetransformation elements are highest among elements mounted on thetiming-converter board 7 and the light source control circuit board 8 inmany cases. Also, these voltage transformation elements are said to besusceptible of mechanical shocks as compared with semiconductor ICs(integrated circuit elements), which are molded with a resin (resinmaterial). It has been described that the protrusions 31 had better beset to be higher than a top end of that element (in other words, ahighest element relative to the upper surface 33 of the third housing3), which determines the height of the liquid crystal display deviceexcept the protrusions. However, directing attention only to breakage ofelements at the time of conveyance, the protrusions 31 may be set higher(for example, even lower than other semiconductor ICs) than an upper endof a highest one among elements mounted on the upper surface 33 of thethird housing 3. Such setting of the protrusions 31 may be altered inits standard in accordance with the specifications of the respectiveliquid crystal display devices (variation of electric circuit elementsas mounted).

In the above description, the protrusions 31 are formed on the uppersurface 33 of the third housing 3 but they may be cut partially at theirside surfaces 34 to have one ends of cut portions bent to a higherposition than the upper surface 33 (in a layout shown in FIGS. 7A and7B) or may be provided on the aprons 32 (may be suitably changed inposition depending upon layouts of the timing-converter board 7 and thelight source control circuit board 8).

(Maintenance of the Light Source Unit)

Having been described with respect to assembly of the liquid crystaldisplay device (fixing of the third housing 3 to the second housing 2)with a second constitution of the invention, securing of the thirdhousing 3 and the second housing 2 is effected separately from securingof the first housing 1 and the second housing 2. This constitution iseffective in reducing a burden in maintenance of the light source unitin the liquid crystal display device products (liquid crystal displaymodules).

FIGS. 9A and 9B are illustrations of a second constitution according tothe invention, FIG. 9A showing the case were a light source unit (thethird housing 3, on which the unit is installed) is removed from theliquid crystal display device and FIG. 9B showing in enlarged scale aconstruction shown by a circle of FIG. 9A. FIG. 9A is equivalent to aconstruction obtained when FIGS. 3H and 3I are reversed up and down.

As described above, the terrace 32 at the other end (peripheral edge, onwhich the data drive ICs are not arranged) of the third housing 3 isfitted into the recess defined by the terrace 15 on the first housing 1and the terrace 221 on the second housing 2. When the screws 322 forsecuring one end (peripheral edge, on which the data drive ICs arearranged) of the third housing 3 to the terrace 22 on the second housing2 are disengaged, the one end of the third housing 3 is lifted as shownin FIG. 9A. The terrace 32 at the other end of the third housing 3 issmall in a distance between the side surface 34 and an end thereof ascompared with the terrace at the one end, and so can be moved in therecess upon lifting of the one end of the third housing 3. The thirdhousing 3 can be disengaged from the second housing 2 (the liquidcrystal display module body MDL) in a stage, in which its one end islifted to some extent.

The third housing 3 having been disengaged from the liquid crystaldisplay module body MDL is placed with the upper surface 33 (surface, onwhich the timing-converter board 7 and the like are mounted) facingdownward, and maintenance and part replacement of the light source unitare carried out. For example, those cold-cathode fluorescent tubes 61having been degraded in lighting performance are replaced by new ones.The third housing 3 shown in the drawings has the above mentionedprotrusions 31 according to the first constitution of the invention, butwhen such protrusions are not provided, a jig for grasping, for example,the terraces 32 on the both ends of the third housing is prepared sothat parts of the timing-converter circuit and the light source controlcircuit, which are installed on the upper surface 33 of the thirdhousing 3, are prevented from striking against working tables and desks.

As apparent from FIGS. 9A and 9B, other parts, such as the liquidcrystal display panel 4 and the optical sheet 5, than parts relating tomaintenance of the light source unit can be subjected to the maintenancework while being fixed to the liquid crystal display module body MDL. Ifthe first housing 1 and the second housing 2 were separated inmaintenance of the light source unit, it would take enormous time forengagement and disengagement of the liquid crystal display panel 4 andthe optical sheet 5, in particular, for positional registering aftermaintenance. As regards the optical sheet 5, while depending upon itsspecification, a displayed image is greatly affected in quality bypositioning of the optical sheet relative to the liquid crystal displaypanel 4 and by dust entering between the optical sheet and the liquidcrystal display panel during the positioning work. The secondconstitution according to the invention reduces a burden on maintenanceand examination of set products, such as personal computers, liquidcrystal display monitors or televisions, by users or maintenanceengineers for the products, even in a state, in which the liquid crystaldisplay module MDL is mounted on the set product.

FIGS. 10A-10C show an example of a monitor making use of the liquidcrystal display device embodying the second constitution according tothe invention. FIG. 10A is a side view, FIG. 10B being a front view (aview seen from the monitor, that is, from a user's side), and FIG. 10Cbeing a side view showing a state, in which the light source unit isremoved in the monitor.

A liquid crystal display monitor 9 is composed of an image display unit91 and a liquid crystal display unit support 92, the former furthercomprising an image display unit front box 911 and an image display unitrear box 912. Mounted on the liquid crystal display unit support are apower source unit (not shown) for converting electric power (forexample, 100V) supplied from outside into a common voltage (for example,12 V) in the liquid crystal display monitor, and an interface circuitfor reception of signals from an external computer.

The liquid crystal display module MDL (profile of the liquid crystaldisplay module MDL is shown by broken lines in FIG. 10B) is fixed insidethe image display unit front box 911 by means of screws 910. The screws910 are used to have a length not reaching the third housing 3 of theliquid crystal display module MDL or contrivance is performed topartially recess the third housing 3 at locations where the screws 910reach. This is because of preventing the screws 910 from making itimpossible to disengage the third housing 3 from the second housing 2.

As shown in FIG. 10C, maintenance of the light source unit of the liquidcrystal display module on the liquid crystal display monitor can beperformed by opening the image display unit front box 911 from the imagedisplay unit rear box 912 fixed to the liquid crystal display unitsupport 92, taking out the back surface of the liquid crystal displaymodule MDL (upper surface side of the third housing 3), and then in thesame manner as described above with reference to FIGS. 9A and 9B.

While the embodiments of the invention have been concretely describedabove, the invention is not limited to the above-mentioned embodimentsand of course can be modified in various manners within the scope notdeparting from the gist of the invention.

As described above, the invention makes parts and kinds of liquidcrystal display devices common to be capable of stably and flexiblycoping with commercial products of computer makers and televisionmakers, which have been promoted in various kinds. Also, it is possibleto simplify maintenance of a liquid crystal display unit mounted oncomputers, display monitors therefor or televisions, and to omitpositional adjustment of a light source unit and a liquid crystaldisplay panel at the time of maintenance.

While we have shown and described several embodiments in accordance withthe present invention, it is understood that the same is not limitedthereto but is susceptible of numerous changes and modifications asknown to those skilled in the art, and we therefore do not wish to belimited to the details shown and described therein but intend to coverall such changes and modifications as are encompassed by the scope ofthe appended claims.

1. A liquid crystal display device comprising: a liquid crystal displaypanel comprising a pair of longer sides, a first shorter side, and asecond shorter side; a first housing comprising a liquid crystal displaywindow; a second housing comprising a first surface and a second surfaceopposed to the first surface; a plurality of light sources disposedimmediately below the liquid crystal display panel, and disposed on thefirst surface of the second housing; and a circuit board comprising alight source control circuit mounted on the second surface of the secondhousing; wherein the plurality of light sources are connected to thecircuit board via lead, wherein the circuit board comprises a pluralityof circuit, and wherein the liquid crystal display panel is fixedbetween the first housing and the second housing, and the second housingcomprises a plurality of protrusions on the second surface that ishigher than the plurality of circuit elements, the circuit board beingarranged between the plurality of protrusions.
 2. A liquid crystaldisplay device according to claim 1, wherein the plurality of circuitelements are voltage transformation circuits mounted on the circuitboard.